Hi,

yes, there is a bus service. Look here:

http://mbusexpres.hit.bg/index3.htm

БУРГАС-ВЕЛИКО ТЪРНОВО = Bourgas - Veliko Turnovo

От Бургас-Автогара "Запад" = From bus-station "west"

От Велико Търново = From Veliko Turnovo

I don't know, if this time-table is up to date.

And I think, there are other bus services.

Bulgarienfan

This time-table is very up to date, only value in winter. Let's wait for summer!